Ancient Chinese text reveals earliest known record of a candidate aurora

There's rarely time to write about every cool science-y story that comes our way. So this year, we're once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2022, each day from December 25 through January 5. Today: New analysis of an ancient Chinese text revealed the earliest candidate aurora yet found, predating the next oldest by three centuries.

According to a paper published in the journal Advances in Space Research, a pair of researchers have identified the earliest description of a candidate Aurora. The likely date of the event is either 977 or 955 BCE, according to the authors. Three centuries later, the Assyrians found the next earliest description of a candidate Aurora.

The northern and southern lights are caused by charged particles from the Sun being dumped into the Earth's magnetosphere. Green, purple, blue, and yellow are some of the colors of the Aurora.

There are different types of Auroral displays, such as a faint glow near the horizon, rarer "picket fence" and " dune" displays, and the most intense one, which appears in the sky as shimmering. It is possible to read a newspaper by their light. That was the case in August and September of 1859, when there was a major geomagnetic storm, the largest ever recorded.

The Bamboo Annals is a chronicle of ancient China, written on bamboo strips, that starts with the age of the Yellow Emperor and goes through the Warring States period, when rival states were engaged in intense competition. The unification of the states happened when the state of Qin was formed. The original text of the Bamboo Annals wasn't discovered until 281CE, after Emperor Qin Shi Huang burned the books and hundreds of Confucian scholars were killed.

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During the Song dynasty, 13 scrolls were lost. Two versions of the Bamboo Annals exist. Two scrolls were printed in the late 16th century. Many scholars think this text is a forgery because of the many discrepancies between its text and portions of the original quoted in older books.

The ancient text was used by Marinus Anthony van der Sluijs and Hisashi Hayakawa. There is a "five-colored light" visible in the northern part of the night sky towards the end of King Zhao's rule. The particles follow the Earth's magnetic field lines and can't be seen in the rest of the world. Powerful storms can cause the Auroral Ovals to expand into lower latitudes. According to the authors, during the 10th century BCE, the north magnetic pole was closer to central China than it is today.

The explicit mention of nighttime observation rules out daytime manifestations of atmospheric optics, which sometimes mimic candidate events, according to the authors. There is a correlation between the occurrence of a multicolored phenomenon in the northern sky during the night and the visual displays of the Auroral display in mid-latitude regions. According to van der Sluijs and Hayakawa, the 16th century current text's translation of the passage in question described the event as a comet instead of a five-colored light.

The book Advances in Space Research was published in 1992. About DOIs can be found in the 10.1016/j.asr.2022.01.020.